Emerson Exchange 365

Ooops I forgot to mention, that the pulsed output from the flow meter will be wired into a wireless device and sent to a WIOC.

DeltaV discrete inputs can be set up as "pulse count input". You then use an AI to read the data.

Lance

In reply to Colin Welsh:

Colin, Since you are connecting to a wireless device, this really becomes a discussion on what WirelessHart device out there takes a pulsed output signal as its process input. Since wireless devices go dormant and wake up to sense and send their data, I don't know that you'll find one that does what you need.

Connecting a pulse signal to a DeltaV system is done using either a DI card, a PCI card (also known as a Multi Function card), or a DI CHARM.
- The DI Card pulse rate is max 75 HZ, so that likely does not serve your need. The DI channel is configured to be a Pulse input and this provides an analog count that is calibrated to the flow rate via a volume per pulse.
- The PCI card provides up to 50KHz, and works with the PCI Block to provide you with the flow rate, as well as a frequency on the pulse train. This is a 4 channel card that is added to the DeltaV LocalBus IO carrier.
- The DI 24VDC Low Side sense CHARM provides up to 10KHz. The DI configuration is set to Pulse Input and behaves like the PCI Card Pulse channel. Use the PCI block to convert to the flowrate.

The CHARM IO is only available with S-series Controllers on DeltaV versions 11 and above. If you have M-series hardware, the Multi Function card would be required. I know this is not the wireless solution you are looking for, but I'm not sure if that exists. If you can find a wired HART device that will take the pulse signal, you could add a Wireless THUMB to it to pull the HART variables and have one of them hold the flow rate value. This would allow the data to go through the WIOC and into DeltaV.

Andre Dicaire

In reply to Andre Dicaire:

If faced with this situation, I'd install a signal conditioner to output a 4-20 from the pulse train and transmit that over wireless.

In reply to Andre Dicaire:

Andre

I am working on a similar application. We have started using pulse output devices for speed switches on some of our mill equipment such as conveyors. I know I've heard of the ability of the M series DI card to read pulses using an AI block but i have never done it. We have the 32 channel, high density, DI card. I just looked in the IO config program and i do not see any option to select a channel to be a pulse input. The only option I see is Discrete Input Channel (HD). Am i missing something obvious? How do I configure it to read pulses?

Thanks in advance!!

In reply to doug bray:

Doug, The 32 channel cards will not provide you with a Pulse Count in option. The 8 channel DI card is only 75 Hz. The MultiFunction card provides a PCI up to 50K Hz. CHARM DI's have 10K Hz speed. When you enable the channel for PCI, you get some added parameters that can be used with the PIN (Pulse Input Block), not the AI block. to provide the analog pulse rate converted to EU based on the pulse. Check out the PIN block in BOL. but also, make sure your DI Channel supports the required pulse rate.

Andre Dicaire

In reply to Andre Dicaire:

Andre, thanks . I've used the Multi card before. I was afraid that was the answer on the 32 channel di card. The speed switches we previously used were just dry contacts back to us. However those switches are expensive and we are trying to use less expensive ones but they are pulse rather than a dry contact. 80% of my DI's are the 32 channel ones and all of the existing speed switches are already wired to them. Thanks again for your feedback.